The present invention relates to a semiconductor substrate transport system, and, more particularly, to a semiconductor substrate transport system usable in semiconductor production apparatuses for subjecting semiconductor substrates to predetermined dry processing.
In semiconductor production apparatus, such as, for example, a dry etching apparatus or a plasma CVD apparatus, for subjecting semiconductor substrates to predetermined processing such as etching and formation of a film by dry processes, semiconductor substrate transport systems are used for carrying the semiconductor substrates into a processing chamber and carrying the processed semiconductor substrates out of the processing chamber. In, for example, Japanese Laid-open Patent Application No. 57-41100, a semiconductor substrate transport system of a so-called belt conveyor type is proposed wherein a belt is endlessly extended over motor driven wheels disposed in opposition to each other, and semiconductor substrates placed on the belt are transported by a conveying force resulting from rotation of the belt. In this proposed system a semiconductor substrate transport system (hereinbelow, termed "first arm conveyor system") wherein an endless chain is extended over gears disposed in opposition to each other and is shifted in both rightward and leftward directions by a reversible motor. An arm has one end thereof mounted on the endless chain and has a vacuum chuck attached to the other end thereof, and a semiconductor substrate attracted and held by the vacuum chuck is transported by the rightward and leftward movements of the arm which are based on the shifts of the endless chain in both the rightward and leftward directions. In, for example, Japanese Laid-open Patent Application No. 56-22374, a semiconductor substrate transport system (hereinbelow, termed "second arm conveyor system") is disclosed wherein a loading motor, disposed on an atmospheric side, and a mechanical chuck, disposed on a vacuum side, are coupled by an arm, while the atmospheric side and the vacuum side are shut off by an O-ring annularly mounted on the arm, and the arm is reciprocated in its longitudinal direction by the loading motor, to thereby transport a semiconductor substrate which is gripped and held by the mechanical chuck. Additionally, in, for example, Japanese Laid-open Utility Model Registration Application No. 57-33002, a semiconductor substrate transport system (hereinbelow, termed "air bearing system") is proposed wherein a semiconductor substrate is floated and transported by the thrust of jets of air.
There are a number of disadvantages in semiconductor substrate transport systems of the aforementioned types.
More particularly, in the belt conveyor system, due to a frictional force which arises between the belt and the driven wheel during the rotation of the belt dust is generated which adheres to and is deposited on the semiconductor substrate. Therefore, the available percentage of the semiconductor substrates processed by the semiconductor production apparatus is relatively low. Moreover, the quantity of dust attributed to the frictional force between the belt and the driven wheel increases with the transport rate of the semiconductor substrates, namely, with the rotational speed of the belt, and the available percentage of the processed semiconductor substrates is further reduced. Therefore, the semiconductor substrates cannot be transported at high speed, and the throughput of the semiconductor substrates to be processed by the semiconductor production apparatus is relatively low.
In the first arm conveyor system, dust also results due to a frictional force which arises between the endless chain and the gear during the turning of the endless chain. For the same reasons as in the belt conveyor system, the available percentage and throughput of the semiconductor substrates processed or to be processed by the semiconductor production apparatus is relatively low.
In the second arm conveyor system, dust also results due to a sliding force which arises between the arm and the O-ring during the transport of the semiconductor substrate, namely, during the reciprocating motion of the arm, and the dust adheres and is deposited on the semiconductor substrate. Therefore, the available percentage of the semiconductor substrates processed by the semiconductor production apparatus is relatively low. With an increase in the transport rate of the semiconductor substrates or the reciprocating speed of the arm, the quantity of the dust attributed to the sliding force between the arm and the O-ring increases more thereby further reducing the available percentage of the processed semiconductor substrates, and the sliding force deteriorates the effectiveness of the O-ring more to shut off the atmospheric side and the vacuum side. Therefore, the semiconductor substrate cannot be transported at high speed, and the throughput of the semiconductor substrates to be processed by the semiconductor production apparatus is relatively low. With the loading motor and mechanical chuck installed on the vacuum side, the O-ring for shutting off the atmospheric side and the vacuum side is unnecessary, and hence, it is possible to avoid the dust ascribable thereto. However, dust appears anew from the sliding part and turning part of the loading motor. Accordingly, the aforementioned disadvantages cannot be eliminated even when the loading motor and mechanical chuck is disposed on the vacuum side.
A disadvantage of the air bearing system resides in the fact that such system cannot be used in a vacuum atmosphere. Moreover, it is necessary for the air for the air bearing system to be extraordinarily clean so as to increase the percentage of processed semiconductor substrates as well as the throughput of the semiconductor substrates processed or to be processed by the semiconductor production apparatus.
An object of the present invention is to provide a semiconductor substrate transport system wherein a linear pulse motor, which is a noncontacting driving device having neither a sliding part, nor a turning part is employed for reciprocatingly driving a semiconductor substrate holder means in a vacuum atmosphere, with the linear pulse motor being disposed in the vacuum atmosphere, thereby suppressing a generation of dust during the transport of semiconductor substrates, namely, during the reciprocating drive of the semiconductor substrate holder means, and to enhance the available percentage and throughput of the semiconductor substrates processed or to be processed by a semiconductor production apparatus.
In accordance with the present invention, a semiconductor substrate transport system is provided which includes a semiconductor substrate holder means for holding semiconductor substrates to be transported, a linear pulse motor for reciprocatingly driving the semiconductor substrate holder means, a pulse oscillator connected to the linear pulse motor, clearance holding means for holding a clearance of the linear pulse motor, and guide means for guiding the reciprocating motion of the linear pulse motor and the semiconductor substrate holding means. The linear pulse motor, the clearance holding means and the guide means are installed within a chamber which is brought into a vacuum atmosphere, whereby the semiconductor substrate holding means is reciprocatingly driven by the linear pulse motor, to suppress the generation of dust during the transport of the semiconductor substrates, namely, during the reciprocating movement of the semiconductor substrate holding means.